Technical Field
[0001] The present invention relates to a curable organopolysiloxane composition and to
an optical semiconductor device having an optical semiconductor element that is sealed
and/or bonded with a cured body of the aforementioned composition.
Background Art
[0003] Curable organopolysiloxane compositions are used for sealing and/or bonding optical
semiconductor elements in optical semiconductor devices having optical semiconductor
elements such as photocouplers, light-emitting diodes, solid-state image pickup elements,
or the like. It is required that cured bodies of such compositions neither absorb
nor scatter the light emitted or received from semiconductor elements. Furthermore,
in order to improve reliability of the optical semiconductor devices, it is desired
that the cured bodies could not discolor or decrease in the bonding strength.
[0004] Japanese Unexamined Patent Application Publication (hereinafter referred to as "Kokai")
2006-342200 discloses a curable organopolysiloxane composition that can form a cured body having
high hardness and high light transmittance. However, the cured body produced from
such a composition can be either easily damaged during manufacture or use of an optical
semiconductor device, or can easily delaminate from the optical semiconductor element
or a package of such element.
[0005] Furthermore, Kokai
2007-63538 and Kokai
2008-120843 disclose curable organopolysiloxane compositions that can form cured bodies having
excellent impact-resistant properties. However, since with the lapse of time such
cured bodies are subject to yellowing, they are not suitable for sealing or bonding
optical semiconductor elements of optical semiconductor devices that are intended
for long-time use at high temperatures.
[0006] WO 2009/017215 A1 would also be useful in understanding of the present invention.
[0007] It is an object of the present invention to provide a curable organopolysiloxane
composition that can form a cured body having long-lasting properties of light transmittance
and bondability, and having relatively low hardness. It is another object to provide
an optical semiconductor device that possesses excellent reliability.
Disclosure of Invention
[0008] The curable organopolysiloxane composition of the invention comprises at least the
following components:
- (A) an alkenyl-containing organopolysiloxane that comprises 40 to 70 wt.% of constituent
(A-1) and 30 to 60 wt.% of constituent (A-2), wherein
constituent (A-1) comprises an organopolysiloxane of the following average compositional
formula:
(R13 SiO1/2)a (R12 SiO2/2)b (R1 SiO3/2)c (SiO4/2)d
where R1 designates phenyl groups, methyl groups, or alkenyl groups having 2 to 10 carbon
atoms; 0.1 to 50 mole % of all R1 groups are alkenyl groups having 2 to 10 carbon atoms; methyl groups constitute 90
mole % or more of the sum of methyl and phenyl groups contained in R1; "a", "b", "c", and "d" are numbers that satisfy the following conditions: 0 ≤ a
≤ 0.05; 0.9 ≤ b ≤ 1; 0 ≤ c ≤ 0.03; 0 ≤ d ≤ 0.03; and a+b+c+d = 1;
constituent (A-2) comprises an organopolysiloxane of the following average compositional
formula:
(R23 SiO1/2)e (R22 SiO2/2)f(R2 SiO3/2)g (SiO4/2)h (H1/2)i
where R2 designates phenyl groups, methyl groups, or alkenyl groups having 2 to 10 carbon
atoms; 5 to 10 mole % of all R2 groups are alkenyl groups having 2 to 10 carbon atoms; methyl groups constitute 90
mole % or more of the sum of methyl and phenyl groups contained in R2; "e", "f', "g", "h" and "i" are numbers that satisfy the following conditions: 0.4
≤ e ≤ 0.6; 0 ≤ f ≤ 0.05; 0 ≤ g ≤ 0.05; 0.4 ≤ h ≤ 0.6; 0.01 ≤ i ≤ 0.05; and e+f+g+h
= 1;
- (B) an organopolysiloxane that contains silicon-bonded hydrogen atoms and comprises
10 to 50 wt.% of constituent (B-1), 50 to 90 wt.% of constituent (B-2), and 0 to 30
wt.% of constituent (B-3), in an amount that the silicon-bonded hydrogen atoms in
component (B) are in the range of 0.5 to 2.0 moles per 1 mole of the total content
of alkenyl groups in component (A), wherein
constituent (B-1) comprises an organopolysiloxane that contains at least 0.5 wt.%
of silicon-bonded hydrogen atoms and that is represented by the following average
molecular formula:
R33 SiO (R32 SiO)j (R3H SiO)k SiR33
where R3 designates phenyl groups or methyl groups; methyl groups constitute 90 mole % or
more of all groups contained in R3; "j" is a number in the range of 0 to 35; and "k" is a number in the range of 5 to
100;
constituent (B-2) comprises an organopolysiloxane that contains at least 0.5 wt.%
of silicon-bonded hydrogen atoms and that is represented by the following average
compositional formula:
(HR42 SiO1/2)l (R43 SiO1/2)m (R42 SiO2/2)n (R4 SiO3/2)o (SiO4/2)p (RSO1/2)q
where R4 designates phenyl groups or methyl groups; methyl groups constitute 90 mole % or
more of all groups contained in R4; R5 designates hydrogen atoms or alkyl groups having 1 to 10 carbon atoms; and "1", "m",
"n", "o", "p" and "q" are numbers that satisfy the following conditions: 0.4 ≤ 1 ≤
0.7; 0 ≤ m ≤ 0.2; 0 ≤ n ≤ 0.05; 0 ≤ o ≤ 0.5; 0.3 ≤ p ≤ 0.6; 0 ≤ q ≤ 0.05; and l+m+n+o+p
= 1;
constituent (B-3) is an organopolysiloxane represented by the following average molecular
formula:
HR62 SiO (R62 SiO)r SiR62H
where R6 represents phenyl groups or methyl groups; methyl groups constitute at least 90%
of all groups contained in R6; and "r" is a number in the range of 10 to 100; and
- (C) a hydrosilylation-reaction catalyst, in an amount sufficient for curing the composition.
[0009] The composition of the invention may be further provided with (D) fumed silica having
BET specific area of 20 to 200 m
2/g and added in an amount of 1 to 10 parts by weight per 100 parts by weight of the
sum of components (A) to (C).
[0010] When the composition of the invention is cured, it forms a cured body that has a
type A durometer hardness in the range of 70 to 90 according to JIS K 6253 and that
is suitable for use as an agent for sealing or bonding optical semiconductor elements,
in particular light emitting diodes.
[0011] The optical semiconductor device of the present invention is characterized by having
optical semiconductor elements sealed and/or bonded with the use of cured bodies of
the aforementioned composition.
Effects of Invention
[0012] The curable organopolysiloxane composition of the present invention is characterized
by forming a cured body having long-lasting properties of light transmittance and
bondability, and having relatively low hardness. The optical semiconductor device
of the invention is characterized by excellent reliability.
Brief Description of the Drawings
[0013] Fig. 1 is a sectional view of a surface-mount light emitting diode (LED) illustrated
as an example of an optical semiconductor device of the invention.
Reference Numerals Used in the Description
[0014]
- 1
- housing made from polyphthalamide resin
- 2
- inner lead
- 3
- die pad
- 4
- bonding material
- 5
- LED chip
- 6
- bonding wire
- 7
- sealing material
Detailed Description of the Invention
[0015] Component (A), which is the main component of the composition of the invention, comprises
an alkenyl-containing organopolysiloxane that consists of constituents (A-1) and (A-2)
which are described below.
[0016] Constituent (A-1) is used for improving handleability of the composition and mechanical
strength of a cured body. This constituent comprises an organopolysiloxane of the
following average compositional formula:
(R
13 SiO
1/2)
a (R
12 SiO
2/2)
b (R
1 SiO
3/2)
c (SiO
4/2)
d
where R
1 designates phenyl groups, methyl groups, or alkenyl groups having 2 to 10 carbon
atoms. The alkenyl groups of R
1 can be represented by vinyl, allyl, butenyl, pentenyl, or hexenyl groups. Vinyl groups
are preferable in view of their reactivity and ease of synthesis. However, 0.1 to
50 mole % of all R
1 groups are alkenyl groups. This is because if the content of the alkenyl groups is
below the recommended lower limit, a cured body of the composition will have low mechanical
strength, and if, on the other hand, the content of the alkenyl group exceeds the
recommended upper limit, a cured body will become brittle. Furthermore, when the sum
of methyl groups and phenyl groups of R
1 is assumed as 100%, the methyl groups should constitute 90 mole % of more. This is
because if the content of methyl groups is below the recommended lower limit, a cured
body of the composition can easily acquire a color at a high temperature. Furthermore,
in the above formula, "a", "b", "c", and "d" are numbers that represent ratios of
siloxane structural units, and that satisfy the following conditions: 0 ≤ a ≤ 0.05;
0.9 ≤ b ≤ 1; 0 ≤ c ≤ 0.03; 0 ≤ d ≤ 0.03; and a+b+c+d = 1. If the value of "a" exceeds
the recommended upper limit, this will lead to significant decrease in viscosity of
this constituent. This, in turn, will either impair handleability of the composition
and make the present constituent volatile, or will decrease the weight of the composition
during curing and reduce hardness of the cured body. If, on the other hand, the values
of "c" and "d" exceed the recommended upper limit, this will increase viscosity of
the present constituent, and will either impair handleability of the composition,
or will make the cured body too brittle. The value of "b" is determined from the values
of "a", "c", and "d". However, if the value of "b" is lower than the recommended lower
limit, it will be impossible to impart either desired viscosity to the composition
or a required hardness or mechanical strength to a cured body. Constituent (A-1) may
have a linear, cyclic, partially cyclic, or a partially branched molecular structure.
This constituent is liquid at 25°C. The viscosity of this constituent at 25°C should
be in the range of 3 to 1,000,000 mPa·s, preferably 5 to 50,000 mPa·s. If the viscosity
is below the recommended lower limit, this will reduce mechanical strength of a cured
body, and, if, on the other hand, the viscosity exceeds the recommended upper limit,
this will impair handleability of the composition.
[0017] Constituent (A-1) may be represented by organopolysiloxanes expressed by the average
compositional formulas given below, where Vi stands for vinyl, Me stands for methyl,
and Ph stands for phenyl.
(ViMe
2 SiO
1/2)
0.01 (Me
2 SiO
2/2)
0.988
(ViMe
2 SiO
1/2)
0.007 (Me
2 SiO
2/2)
0.993
(ViMe
2) SiO
1/2)
0.004 (Me
2 SiO
2/2)
0.996
(Me
3 SiO
1/2)
0.007 (Me
2 SiO
2/2)
0.983 (MeVi SiO
2/2)
0.010
(Me
3 SiO
1/2)
0.01 (MeVi SiO
1/2)
0.01 (Me
2 SiO
2/2)
0.96 (Me SiO
3/2)
0.02
(ViMe
2 SiO
1/2)
0.005 (Me
2 SiO
2/2)
0.895 (MePh SiO
2/2)
0.100
[0018] Furthermore, constituent (A-1) may be represented by organopolysiloxanes expressed
by the average molecular formulas given below, Vi and Me are the same as defined above.
(MeVi SiO
2/2)
3
(MeVi SiO
2/2)
4
(MeViSiO
2/2)
5
[0019] Constituent (A-2) is an organopolysiloxane that is intended for imparting hardness
and mechanical strength to a cured body of the composition. This constituent is represented
by the following average compositional formula:
(R
23 SiO
1/2)
e (R
22 SiO
2/2)
f(R
2 SiO
3/2)
g (SiO
4/2)
h (HO
1/2)
i
[0020] In this formula, R
2 designates phenyl groups, methyl groups, or alkenyl groups having 2 to 10 carbon
atoms. The alkenyl groups of R
2 can be represented by vinyl, allyl, butenyl, pentenyl, or hexenyl groups. Vinyl groups
are preferable in view of their reactivity and ease of synthesis. However, 5 to 10
mole % of all R
2 groups are alkenyl groups. This is because if the content of the alkenyl groups is
below the recommended lower limit, a cured body of the composition will have low hardness
and mechanical strength, and if, on the other hand, the content of the alkenyl group
exceeds the recommended upper limit, a cured body will become brittle. Furthermore,
when the sum of methyl groups and phenyl groups of R
2 is assumed as 100%, the methyl groups should constitute 90 mole % of more. This is
because if the content of methyl groups is lower than the recommended limit, a cured
body of the composition can easily acquire a color at a high temperature. Furthermore,
in the above formula, "e", "f", "g", "h" and "i" are numbers that represent ratios
of siloxane structural units and hydroxyl groups, and that satisfy the following conditions:
0.4 ≤ e ≤ 0.6; 0 ≤ f ≤ 0.05; 0 ≤ g ≤ 0.05; 0.4 ≤ h ≤ 0.6; 0.01 ≤ i ≤ 0.05; and e+f+g+h
=1. If the value of "e" is below the recommended lower limit, this will reduce mechanical
strength of a cured body, and if, on the other hand, the value of "e" exceeds the
recommended upper limit, it will be impossible to impart to a cured body a sufficient
hardness. If the value of "f" exceeds the recommended upper limit, it will be impossible
to impart to a cured body a sufficient hardness. If the value of "g" exceeds the recommended
upper limit, this will lower mechanical strength of a cured body. If the value of
"h" is below the recommended lower limit, it will be impossible to impart to a cured
body a sufficient hardness, and if, on the other hand, the value of "h" exceeds the
recommended upper limit, it will impair dispersibility of the component in the composition
and will reduce mechanical strength of a cured body of the composition. Finally, in
order to provide the composition with good bondability, it is important to maintain
the value of "i" within the recommended range. If the value of "i" is below the recommended
lower limit, it will be impossible to provide the composition with desired bonding
properties, and if, on the other hand, the value of "i" exceeds the recommended upper
limit, this will impair dispersibility of this constituent in the composition and
will not allow imparting desired mechanical strength and bonding properties to a cured
body of the composition. Constituent (A-2) may have a branched or net-like molecular
structure. There are no special restrictions with regard to viscosity of this constituent
at 25°C and it may be liquid or solid provided that it is miscible with constituent
(A-1).
[0021] Constituent (A-2) may be represented by organopolysiloxanes expressed by the average
compositional formulas given below, where Vi, Me, and Ph are the same as defined above.
(ViMe
2 SiO
1/2)0.10 (Me
3 SiO
1/2)
0.33 (SiO
4/2)
0.
57 (HO
1/2)
0.
03
(ViMe
2 SiO
1/2)
0.13 (Me
3 SiO
1/2)
0.35 (SiO
4/2)
0.52 (HO
1/2)
0.02
(ViMePh SiO
1/2)
0.10 (Me
3 SiO
1/2)
0.33 (SiO
4/2)
0.57 (HO
1/2)
0.03
(ViMe
2 SiO
1/2)
0.09 (Me
3 SiO
1/2)
0.31 (SiO
4/2)
0.60 (HO
1/2)
0.04
(ViMe
2 SiO
1/2)
0.10 (Me
3 SiO
1/2)
0.40 (SiO
4/2)
0.50 (HO
1/2)
0.03
[0022] It is recommended that component (A) contains 40 to 70 wt.% of constituent (A-1)
and 30 to 60 wt.% of constituent (A-2), and preferably 45 to 65 wt.% of constituent
(A-1) and 35 to 55 wt.% of constituent (A-2). If the content of constituent (A-1)
exceeds the recommended upper limit, it will be impossible to impart a desired hardness
and mechanical strength to a cured body of the composition, and if, on the other hand,
the content of constituent (A-1) is below the recommended lower limit, this will impair
handleability of the composition and impart brittleness to a cured body.
[0023] It is not necessary to premix constituents (A-1) and (A-2) of component (A) if the
composition can be eventually prepared in a state of high uniformity. From the viewpoint
of good handleability, component (A) should be liquid at 25°C and have a viscosity
in the range of 100 to 5,000,000 mPa·s, preferably 500 to 100,000 mPa·s.
[0024] Component (B) is used in the composition as a cross-linking agent. It comprises an
organopolysiloxane that has silicon-bonded hydrogen atoms and consists of constituents
(B-1), (B-2), and, if necessary, constituent (B-3).
[0025] Constituent (B-1) acts not only as a cross-linking agent but also as an efficient
interfacial bonding improver. This constituent comprises an organopolysiloxane that
is represented by the following average molecular formula:
R
33 SiO (R
32 SiO)
j (R
3H SiO)
k SiR
33
[0026] In this formula, R
3 designates phenyl groups or methyl groups; methyl groups constitute 90 mole % or
more of all groups contained in R
3. If the content of methyl groups is below the recommended limit, a cured body will
acquire a color at a high temperature. In this formula, "j" is a number in the range
of 0 to 35; and "k" is a number in the range of 5 to 100. If the value of "j" exceeds
the recommended upper limit, it will be impossible to provide the composition with
good bondability. If the value of "k" is below the recommended lower limit, it will
be impossible to provide the composition with good bondability, and if, on the other
hand, the value of "k" exceeds the recommended upper limit, a cured body will be obtained
with low mechanical strength. Furthermore, the content of silicon-bonded hydrogen
atoms should be equal to or greater than 0.5 wt.%. If the content of silicon-bonded
hydrogen atoms is below 0.5 wt.%, it will be difficult to provide the composition
with good bondability. It is recommended that constituent (B-1) be liquid at 25°C
and have viscosity at 25°C in the range of 3 to 10,000 mPa·s, preferably 5 to 5,000
mPa·s. If the viscosity is below the recommended lower limit, a cured body, this will
impair mechanical strength and bonding strength, and if, on the other hand, the viscosity
exceeds the recommended upper limit, this will impair handleability of the composition.
[0027] Constituent (B-1) may be represented by organopolysiloxanes expressed by the average
molecular formulas given below, where Me and Ph are the same as defined above.
Me
3 SiO (MeH SiO)
10 SiMe
3
Me
3 SiO (MeH SiO)
80 SiMe
3
Me
3 SiO (Me
2 SiO)
30(MeH SiO)
30 SiMe
3
PhMe
2 SiO (MeH SiO)
35 SiPhMe
2
[0028] Constituent (B-2) acts not only as a cross-linking agent but also as an efficient
agent for improving mechanical strength of a cured body as well as aggregation and
bonding properties. Constituent (B-2) comprises an organopolysiloxane that is represented
by the following average compositional formula:
(HR
42 SiO
1/2)
l (R
43 SiO
1/2)
m (R
42 SiO
2/2)
n (R
4 SiO
3/2)
o (SiO
4/2)
p (R
5O
1/2)
q
[0029] In this formula, R
4 designates phenyl groups or methyl groups. Methyl groups constitute 90 mole % or
more of all groups contained in R
4. If the content of methyl groups is below the recommended limit, this may color the
cured body at a high temperature. In the above formula, R
5 designates hydrogen atoms or alkyl groups having 1 to 10 carbon atoms. The alkyl
groups of R
5 having 1 to 10 carbon atoms are represented by methyl, ethyl, and isopropyl groups.
Furthermore, in the formula, "1", "m", "n", o", "p" and "q" are numbers that represent
ratios of siloxane structural units and hydroxyl groups or alkoxy groups, and that
satisfy the following conditions: 0.4 ≤ 1 ≤ 0.7; 0 ≤ m ≤ 0.2; 0 ≤ n ≤ 0.05; 0 ≤ or
≤ 0.5; 0.3 ≤ p ≤ 0.6; 0 ≤ q ≤ 0.05; and l+m+n+o+p = 1. If the value of "1" is below
the recommended lower limit, it will be impossible to achieve a desired hardness,
and if, on the other hand, the value of "1" exceeds the recommended upper limit, this
will reduce molecular weight of the present constituent and will not allow imparting
a sufficient mechanical strength to a cured body. Furthermore, if the value of "m"
exceeds the recommended upper limit, it will be impossible to achieve a desired hardness.
If the value of "n" exceeds the recommended upper limit, it will be impossible to
achieve a desired hardness. If the value of "o" exceeds the recommended upper limit,
this will impair dispersibility of the constituent and will not allow imparting a
sufficient mechanical strength to a cured body. If the value of "p" is below the recommended
lower limit, it will be impossible to achieve as a desired hardness, and if, on the
other hand, the value of "p" exceeds the recommended upper limit, this will impair
dispersibility of the present constituent in the composition and will not allow obtaining
a desired mechanical strength. Finally, if the value of "q" exceeds the recommended
upper limit, this will reduce molecular weight of the constituent and will not allow
imparting a sufficient mechanical strength to a cured body. The present constituent
should contain at least 0.5 wt.% of silicon-bonded hydrogen atoms. If the content
of silicon-bonded hydrogen atoms is below 0.5 wt.%, it will be impossible to impart
sufficient mechanical strength to a cured body. In order to improve miscibility of
the present constituent with the composition, this constituent should be liquid or
solid at 25°C.
[0030] Constituent (B-2) may be represented by organopolysiloxanes expressed by the average
compositional formulas given below, where Me and Ph are the same as defined above.
(HMe
2 SiO
1/2)
0.67 (SiO
4/2)
0.33
(HMe
2 SiO
1/2)
0.50 (Me
3 SiO
1/2)
0.17 (SiO
4/2)
0.33
(HMe
2 SiO
1/2)
0.65 (Ph SiO
3/2)
0.05 (SiO
4/2)
0.30
[0031] Constituent (B-3) is an arbitrary component, which is used for controlling hardness
of a cured body. This constituent is an organopolysiloxane represented by the following
average molecular formula:
HR
62 SiO (R
62 SiO)
r SiR
62H
where R
6 designates phenyl or methyl groups and where methyl groups constitute at least 90%
of all groups contained in R
6. If the content of methyl groups is below the recommended lower limit, this will
color a cured body at a high temperature. In the above formula, "r" designates a number
in the range of 10 to 100. If "r" is below the recommended lower limit, it will be
difficult to provide a cured body with a desired hardness, and if, on the other hand,
the value of "r" exceeds the recommended upper limit, a cured body will lose its mechanical
strength.
[0032] Constituent (B-3) can be exemplified by organopolysiloxanes that are expressed by
the following average molecular formulas, where Me and Ph are the same as defined
above:
HMe
2 SiO (Me
2 SiO)
20 SiMe
2H
HMe
2 SiO (Me
2 SiO)
80 SiMe
2H
HMe
2 SiO (Me
2 SiO)
50 (MePh SiO)
5 SiMe
2H
[0033] Component (B) contains 10 to 50 wt.% of constituent (B-1), 50 to 90 wt.% of constituent
(B-2), and 0 to 30 wt.% of constituent (B-3), preferably 15 to 35 wt.% of constituent
(B-1), 65 to 85 wt.% of constituent (B-2), and 0 to 25 wt.% of constituent (B-3).
If the content of constituent (B-1) exceeds the recommended upper limit, this will
reduce mechanical strength of a cured body, and if, on the other hand, the content
of constituent (B-1) is below the recommended lower limit, this will reduce bonding
properties of a cured body. If the content of constituent (B-2) exceeds the recommended
upper limit, this will reduce bonding properties of a cured body, and if, on the other
hand, the content of constituent (B-2) is below the recommended lower limit, this
will reduce mechanical strength of a cured body. If the content of constituent (B-3)
exceeds the recommended upper limit, this will reduce hardness of a cured body. It
is not necessary to premix the aforementioned constituents of component (B) if it
is eventually possible of obtained the final composition in a state of high uniformity.
Component (B) is liuid at 25°C. From the viewpoint of good handleability, component
(B) should be liquid at 25°C and have a viscosity in the range of 5 to 100,000 mPa·s,
preferably 10 to 50,000 mPa·s.
[0034] Component (B) is added in such an amount that the silicon-bonded hydrogen atoms are
in the range of 0.5 to 2.0 moles, preferably 0.8 to 1.8 moles, per 1 mole of the total
content of alkenyl groups in component (A). If the content of component (B) is below
the recommended lower limit, or exceeds the recommended upper limit, it will be impossible
to impart to a cured body of the composition the desired hardness, mechanical characteristics,
and bonding properties.
[0035] Component (C) is a hydrosilylation-reaction catalyst that is used for accelerating
hydrosilylation reaction of the composition. Such a catalyst can be exemplified by
a platinum-based catalyst, platinum-based compound catalyst, metallic platinum catalyst,
rhodium-based catalyst, or a palladium-based catalyst. From the viewpoint of efficient
acceleration of the hydrosilylation reaction of components (A) and (B) and thus for
accelerated curing of the composition, it is recommended to employ a platinum-based
catalyst. Such a catalyst can be represented by fine platinum powder, platinum black,
chloroplatinic acid, an alcohol-modified chloroplatinic acid, a diolefin complex of
chloroplatinic acid, an olefin complex of platinum; platinum bis(acetoacetate), platinum
bis(acetoacetonate), or a similar platinum-carbonyl complex; a complex of chloroplatinic
acid and divinyl-tetramethyl disiloxane, a complex of chloroplatinic acid and tetravinyl-tetramethyl-cyclotetrasilane,
or a similar complex of chloroplatinic acid and alkenylsiloxane; a complex of platinum
and divinyltetramethyl-disiloxane, a complex of platinum and tetravinyltetramethyl-cyclotetrasiloxane,
or a similar complex of platinum and alkenylsiloxane; a complex of chloroplatinic
acid and acetylene alcohol, etc. From the viewpoint of hydrosilylation efficiency,
it is recommended to use a complex of platinum and an alkenylsiloxane.
[0036] The alkenylsiloxane may be exemplified by the following compounds: 1,3-divinyl-1,1,3,3-tetramethyldisiloxane;
1,3,5,7-tetramethyl-1,3,5,7-tetravinyl cyclotetrasiloxane; alkenylsiloxane wherein
a part of its methyl groups is substituted with ethyl groups, phenyl groups, etc.;
or a similar substituted alkenylsiloxane oligomer; or an alkenylsiloxane oligomer
wherein vinyl groups of its alkenylsiloxane are substituted with allyl, hexenyl, or
similar groups. Due to the high stability of platinum-alkenylsiloxane complexes, it
is recommended to use 1,3-divinyl-1,1,3,3-tetramethyldisiloxane.
[0037] Furthermore, in order to further improve the stability of platinum-alkenylsiloxane
complexes, they can be combined with 1,3-divinyl-1,1,3,3-tetramethyldisiloxane, 1,3-diallyl-1,1,3,3-tetramethyldisiloxane,
1,3-divinyl-1,3-dimethyl-1,3-diphenyldisiloxane, 1,3-divinyl-1,1,3,3-tetraphenyldisiloxane,
1,3,5,7-tetramethyl-1,3,5,7-tetravinylcyclotetrasiloxane, or similar alkenylsiloxane
oligomers or organosiloxane oligomers such as dimethylsiloxane oligomers, especially
alkenylsiloxane oligomers.
[0038] There are no special restriction with regard to the amount in which component (C)
can be used, provided that it accelerates curing of the composition. More specifically,
it is recommended to add component (C) in such an amount that in terms of weight units
the content of platinum-type metal atoms, in particular platinum atoms of this component
is in the range of 0.01 to 500 ppm, preferably 0.01 to 100 ppm, and more preferably
0.1 to 50 ppm. If the content of component (C) is below the recommended lower limit,
it will be difficult to provide sufficient curing, and if, on the other hand, the
content of component (C) exceeds the recommended upper limit, this will lead to coloration
of the cured body.
[0039] In order to improve handleability and bonding properties of the composition, it may
be further provided with (D) fumed silica having BET specific area in the range of
20 to 200 m
2/g. This component should be used in an amount of 1 to 10 parts by weight per 100
parts by weight of the sum of components (A), (B), and (C). If component (D) is used
in such an amount that the BET specific area thereof is below or above the recommended
range, this will impair handleability and will not allow obtaining a desired viscosity
of the composition. Furthermore, if the content of component (D) exceeds the recommended
upper limit, this will impair light transmitting properties.
[0040] In order to extend the pot life and storage stability at room temperature, the composition
can be further provided with component (E) such as 1-ethynylcyclohexan-1-ol, 2-methyl-3-butyn-2-ol,
3,5-dimethyl-1-hexyn-3-ol, 2-phenyl-3-butyn-2-ol, or similar alkyne alcohols; 3-methyl-3-penten-1-yne,
3,5-dimethyl-3-hexen-1-yne, or similar ene-yne compounds; 1,3,5,7-tetramethyl-1,3,5,7-tetravinylcyclotetrasiloxane,
1,3,5,7-tetramethyl-1,3,5,7-tetrahexenylcyclotetrasiloxane, or similar methylalkenylsiloxane
oligomers; dimethyl bis(3-methyl-1-butyn-3-oxy)silane, methylvinyl bis(3-methyl-1-butyn-3-oxy)silane,
or similar alkynoxysilanes; benzotriazole, or similar hydrosilylation reaction inhibitors.
[0041] Component (E) is used in an amount sufficient for inhibiting gelling or curing the
composition during mixing of components (A), (B), and (C) and also in an amount needed
for providing long-term storage of the composition. More specifically, it is recommended
to add this component in an amount of 0.0001 to 5 parts by weight, preferably 0.01
to 3 parts by weight per 100 parts by weight of the sum of components (A), (B), and
(C).
[0042] Moreover, to further improve bonding to the substrate that is in contact with the
composition during curing, the composition may be combined with (F) an adhesion promoter.
Such an adhesion promoter may be one known in the art and used for addition to hydrosilylation-reaction
curable organopolysiloxane compositions.
[0043] Component (F) may be exemplified by the following compounds: organosilanes or organosiloxane
oligomers having 4 to 20 silicon atoms and a linear, branched, or cyclic molecular
structure and containing trialkoxysiloxy groups (such as trimethoxysiloxy groups or
triethoxysiloxy groups) or trialkoxysilylalkyl groups (such as trimethoxysilylethyl
groups or triethoxysilylethyl groups) and hydrosilyl groups or alkenyl groups (such
as vinyl groups or allyl groups); organosilanes or organosiloxane oligomers having
4 to 20 silicon atoms and a linear, branched, or cyclic molecular structure and containing
trialkoxysiloxy groups or trialkoxysilylalkyl groups and methacryloxyalkyl groups
(such as 3-methacryloxypropyl groups); organosilanes or organosiloxane oligomers having
4 to 20 silicon atoms and a linear, branched, or cyclic molecular structure and containing
trialkoxysiloxy groups or trialkoxysilylalkyl groups and epoxy-containing alkyl groups
(such as 3-glycidoxypropyl groups, 4-glycidoxybutyl groups, 2-(3,4-epoxycyclohexyl)ethyl
groups, or 3-(3,4-epoxycyclohexyl)propyl groups); reaction products of aminoalkyltrialkoxysilane
and epoxy-bonded alkyltrialkoxysilane; or epoxy-containing ethylpolysilicate. Specific
examples are the following compounds: vinyltrimethoxysilane, allyltrimethoxysilane,
allyltriethoxysilane, hydrogentriethoxysilane, 3-glycidoxypropyltrimethoxysilane,
3-glycidoxypropyltriethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-methacryloxypropyltrimethoxysilane,
3-methacryloxypropyltriethoxysilane, reaction products of 3-glycidoxypropyltriethoxysilane
and 3-aminopropyltriethoxysilane; condensation reaction products of 3-glycidoxypropyltrimethoxysilane
and methylvinylsiloxane oligomer capped with silanol groups; condensation reaction
products of 3-methacryloxypropyltriethoxysilane and methylvinylsiloxane oligomer capped
with silanol groups; and tris(3-trimethoxysilylpropyl)isocyanurate.
[0044] From the viewpoint of preventing a decrease in resistance to yellowing and in light
transparency, when a cured body is used over a long time at elevated temperatures,
it is preferable that component (F) does not contain active nitrogen atoms, e.g.,
amino groups. This adhesion promoter is preferably a low-viscosity liquid that has
a viscosity at 25°C in the range of 1 to 500 mPa·s.
[0045] Component (F) should be added in amounts that do not impair curing properties, in
particular do not cause change of color in a cured body. More specifically, it should
be added in an amount of 0.01 to 5 parts by weight, preferably 0.1 to 3 parts by weight,
per 100 parts by weight of the sum of components (A), (B), and (C).
[0046] Within the limits not contradicting with the object of the invention, besides component
(D), the composition may contain other arbitrary components such as silica, glass,
zinc oxide or similar inorganic fillers; silicone rubber powder; silicone resin, polymethacrylate
resin, or similar resin powders; heat-resistant agents, dyes, pigments, flame retarders,
solvents, etc.
[0047] From the viewpoint of handling, it is recommended that the composition is liquid
and have a viscosity at 25°C in the range of 10 to 1,000,000 mPa·s. If the composition
is intended for use as a sealant for optical semiconductor elements, it should have
a viscosity at 25°C in the range of 100 to 10,000 mPa·s, and if it is intended for
use as a bonding agent for optical semiconductor elements, it should have a viscosity
at 25°C in the range of 1,000 to 500,000 mPa·s.
[0048] The composition is cured by retaining at room temperature or by heating. For acceleration
of curing, it is recommended to cure the composition by heating. The heating temperature
should be in the range of 50 to 200°C.
[0049] The composition provides excellent bonding durability, with respect to steel, stainless
steel, aluminum, copper, silver, titanium, titanium alloy or other metals or alloys;
silicon semiconductors, gallium-phosphorus-based semiconductors, gallium-arsenide-based
semiconductors, gallium-nitride-based semiconductors, or similar semiconductor elements;
ceramics, glass, thermosetting resins, and thermoplastic resins that contain polar
groups, and in particular if the above objects are subject to heating-cooling cycles.
[0050] It is recommended that curing of the composition produce a cured body having hardness
measured by type A durometer in accordance with JIS K 6253 in the range of 70 to 90.
If the cured body has the hardness below the recommended lower limit, it will have
poor cohesion and insufficient strength and bonding capacity, and if, on the other
hand, the hardness exceed the recommended upper limit, a cured body will acquire brittleness,
and it will be impossible to provide sufficient bonding properties.
[0051] The following is a detailed description of an optical semiconductor device of the
invention.
[0052] The optical semiconductor device of the invention comprises an optical semiconductor
element that is either sealed in a housing by a cured body of a sealing material formed
from the composition of the present invention, or is bonded to the housing with a
cured body of a bonding material formed from the composition of the invention. The
optical semiconductor element may comprise a light-emitting diode (LED), semiconductor
laser, photodiode, photo transistor, solid-state image pickup elements, or a photo-coupler
light emitter and receiver. Most suitable application is a LED.
[0053] Since in a LED the light is emitted from the semiconductor in a vertical and in a
horizontal direction, it is required that the parts of the device be made from materials
that do not absorb the light and have either high light transmittance or high coefficient
of light reflection. A substrate that supports the optical semiconductor element is
also not an exception from this rule. Such a substrate can be made from silver, gold,
copper, or another electrically conductive metal; aluminum, nickel or another non-electroconductive
metal; PPA (Polyphthalamide), LCP (Liquid Crystal Polymer), or another thermoplastic
resin mixed with a white pigment; epoxy resin, BT resin, polyimide resin, silicone
resin, or a similar thermosetting resin mixed with a white pigment; alumina, alumina
nitride, or similar ceramics. Since the composition of the invention provides good
bonding to semiconductor elements and substrates, it improves reliability of the obtained
optical semiconductor device.
[0054] The optical semiconductor device of the invention is described in more detail with
reference to Fig. 1. Fig. 1 is a sectional view of a single surface-mount type LED
shown as a typical example of an optical semiconductor device. The LED of Fig. 1 comprises
a LED chip 5 which is die-bonded to a die pad 3 through a bonding material 4 inside
a housing 1 made from a polyphthalamide resin (PPA). The LED chip 5, in turn, is wire-bonded
to inner leads 2 by bonding wires 6, and along with the inner walls of the housing
are sealed with a sealing material 7. In the LED of the invention, the composition
that is used for forming the bonding material 4 and/or the sealing material 7 is the
curable organopolysiloxane composition of the present invention.
Examples
[0055] The curable organopolysiloxane composition of the present invention and the optical
semiconductor device of the invention will be further illustrated in more details
with reference to application and comparative examples. In these application and comparative
examples, the values of viscosity corresponds to 25°C.
[0056] Listed below are formulas of the constituents that were used for the preparation
of curable organopolysiloxane compositions shown in the application and comparative
examples, wherein Vi stands for vinyl groups, Me stands for methyl groups, and Ph
stands for phenyl groups; Vi% shows the percentage of vinyl groups (mole %) in all
organic groups, and Me% shows the percentage of methyl groups (mole %) in the sum
of methyl groups and phenyl groups. Furthermore, in the tables, the SiH/Vi ratio is
the ratio of the total number of silicon-bonded hydrogen atoms in constituents (b-1)
to (b-6) to 1 mole of the sum of vinyl groups in constituents (a-1) to (a-9) contained
in the composition.
| Constituent (a-1): |
organopolysiloxane (Vi% = 2.06 mole %; Me% = 100 mole %) having viscosity of 60 mPa·s
and represented by the following average compositional formula: |
| |
(Me2Vi SiO1/2)0.042 (Me2 SiO2/2)0.958 |
| Constituent (a-2): |
organopolysiloxane (Vi% = 0.60 mole %; Me% = 100 mole %) having viscosity of 550 mPa·s
and represented by the following average compositional formula: |
| |
(Me2Vi SiO1/2)0.012 (Me2Si2/2)0.988 |
| Constituent (a-3): |
organopolysiloxane (Vi% = 50 mole %; Me% = 100 mole %) having viscosity of 4 mPa·s
and represented by the following average molecular formula: |
| |
(MeVi SiO2/2)4 |
| Constituent (a-4): |
organopolysiloxane (Vi% = 5.8 mole %; Me% = 100 mole %) which is solid at 25°C and
is represented by the following average compositional formula: |
| |
(Me2Vi SiO1/2)0.09 (Me3 SiO1/2)0.43 (SiO4/2)0.48 (HO1/2)0.03 |
| Constituent (a-5): |
organopolysiloxane (Vi% = 6.1 mole %; Me% = 100 mole %) which is solid at 25°C and
is represented by the following average compositional formula: |
| |
(Me2Vi SiO1/2)0.10 (Me3 SiO1/2)0.45 (SiO4/2)0.45 (HO1/2)0.02 |
| Constituent (a-6): |
organopolysiloxane (Vi% = 5.8 mole %; Me% = 100 mole %) which is solid at 25°C and
is represented by the following average compositional formula: |
| |
(Me2 Vi SiO1/2)0.09 (Me3 SiO1/2)0.43 (SiO4/)0.48 (H1/2)0.005 |
| Constituent (a-7): |
organopolysiloxane (Vi% = 6.4 mole %; Me% = 100 mole %) which is solid at 25°C and
is represented by the following average compositional formula: |
| |
(Me2Vi SiO1/2)0.10 (Me3 SiO1/2)0.42 (SiO4/2)0.48 (HO1/2)0.07 |
| Constituent (a-8): |
organopolysiloxane (Vi% = 8.5 mole %; Me% = 100 mole %) which is solid at 25°C and
is represented by the following average compositional formula: |
| |
(Me2Vi SiO1/2)0.17 (Me3 SiO1/2)0.50 (SiO4/2)0.33 (HO1/2)0.04 |
| Constituent (a-9): |
organopolysiloxane (Vi% = 4.8 mole %; Me% = 100 mole %) which has viscosity of 500
mPa·s at 25°C and is represented by the following average compositional formula: |
| |
(Me2Vi SiO1/2)0.05 (Me3 SiO1/2)0.30 (SiO4/2)0.65 (HO1//2)0.03 |
| Constituent (b-1): |
organopolysiloxane (Me% = 100 mole %) which has viscosity of 10 mPa·s, contains 1.3
wt.% of silicon-bonded hydrogen atoms, and is represented by the following average
molecular formula: |
| |
Me3 SiO (MeH SiO)10 SiMe3 |
| Constituent (b-2): |
organopolysiloxane (Me% = 100 mole %) which has viscosity of 200 mPa·s, contains 0.72
wt.% of silicon-bonded hydrogen atoms, and is represented by the following average
molecular formula: |
| |
Me3 SiO (Me2 SiO)30 (MeH SiO)30 SiMe3 |
| Constituent (b-3): |
organopolysiloxane (Me% = 100 mole %) which has viscosity of 200 mPa·s, contains 0.34
wt.% of silicon-bonded hydrogen atoms, and is represented by the following average
molecular formula: |
| |
Me3 SiO (Me2 SiO)45 (MeH SiO)15 SiMe3 |
| Constituent (b-4): |
organopolysiloxane (Me% = 100 mole %) which has viscosity of 120 mPa·s, contains 1.03
wt.% of silicon-bonded hydrogen atoms, and is represented by the following average
compositional formula: |
| |
(HMe2 SiO1/2)0.67 (SiO4/2)0.33 |
| Constituent (b-5): |
organopolysiloxane (Me% = 100 mole %) which has viscosity of 130 mPa·s, contains 0.74
wt.% of silicon-bonded hydrogen atoms, and is represented by the following average
compositional formula: |
| |
(HMe2 SiO1/2)0.50 (Me3 SiO1/2)0.17 (SiO4/2)0.33 |
| Constituent (b-6): |
organopolysiloxane (Me% = 75 mole %) which has viscosity of 200 mPa·s, contains 0.65
wt.% of silicon-bonded hydrogen atoms, and is represented by the following average
compositional formula: |
| |
(HMe2 SiO1/2)0.60 (PhSiO3/2)0.40 |
| Constituent (c): |
1.3-divinyl-1,1,3,3-tetramethyldisiloxane solution of complex of platinum and 1,3-divinyl-1,1,3,3-tetramethyldisiloxane
(contains about 4 wt.% of metallic platinum) |
| Constituent (d-1): |
fumed silica having BET surface area in the range of 115 to 165 m2/g and hydrophobized by surface treatment with hexamethyl disilazane (RX200, the product
of Nippon Aerosil Co., Ltd.) |
| Constituent (d-2): |
fumed silica having BET surface area in the range of 30 to 50 m2/g and hydrophobized by surface treatment with hexamethyl disilazane (NAX50, the product
of Nippon Aerosil Co., Ltd.) |
| Constituent (e): |
1-ethynylcyclohexan-1-ol |
| Constituent (f): |
condensation reaction product of 3-glycidoxypropyltrimethoxysilane and methylvinylsiloxane
oligomer capped at both molecular terminals with silanol groups and having viscosity
of 30 mPa·s. |
[0057] Viscosity of the curable organopolysiloxane compositions, as well as hardness, light
transmittance, and bonding strength of the cured bodies mentioned in the application
and comparative examples were measured by the methods described below.
[Viscosity of the Curable Organopolysiloxane Composition]
[0058] This characteristic was measured after the preparation of the curable organopolysiloxane
composition within 30 min. by means of a viscometer (AR-550, the product of TA Instrument
Co., Ltd.) and by using a 2° cone plate of 20 mm diameter at a shear speed of 10 (1/s).
[Hardness of Cured Body]
[0059] The curable organopolysiloxane was formed into a cured sheet-like body by press forming
for 1 hour at 150°C, and the latter was used for measuring hardness with type A durometer
according to JIS K 6253.
[0060] Furthermore, the sheet-like cured body was retained for 1,000 hours in an oven at
150°C, and then hardness after heat-resistance test was measured by the same method
as mentioned above.
[Light-Transmitting Properties of Cured Body]
[0061] The curable organopolysiloxane composition was sandwiched between two glass plates
and cured by holding it for 1 hour at 150°C. Light-transmitting properties of the
obtained cured body were measured at 25°C by a self-recording spectrophotometer (optical
path: 0.1 cm) capable of measuring at any wavelength of visible light (the wavelength
range of 400 nm to 700 nm). Light transmission through the cured body was determined
by subtracting light transmission through the glass only from light transmission through
the glass and the composition. The light transmittance obtained for wavelength 450
nm is shown in Table 1.
[0062] Furthermore, the aforementioned cured body was retained for 1,000 hours in an oven
at 150°C, and then light transmittance after heat-resistance test was measured by
the same method as mentioned above.
[Bonding Strength of Cured Body]
[0063] Spacers made from polytetrafluoroethylene (width: 10 mm; length:20 mm; thickness:
1 mm) were sandwiched between two silver-plated steel plates (width: 25 mm; length:
50 mm; thickness: 1 mm). The gap between the plates was filled with the curable organopolysiloxane
composition, the plates were clipped together, and the composition was cured by retaining
the unit for 1 hour at 150°C in a hot-air-circulation type oven. After cooling to
room temperature, the clip and the spacers were removed, and the bonding strength
of a cured body was measured by stretching the obtained specimen in mutually opposite
horizontal directions in a tensile test machine.
[0064] Furthermore, the aforementioned specimen was retained for 1000 hours in an oven at
150°C, and then the bonding strength after heat-resistance test was measured by the
same method as mentioned above.
[Application Examples 1 to 4, Comparative Examples 1 to 6]
[0065] Curable organopolysiloxane compositions were prepared with component ratios shown
in Table 1. Properties of cured bodies measured as described above are also shown
in Table 1.

[Application Examples 5 to 8, Comparative Examples 7 to 12]
[0066] Curable organopolysiloxane compositions were prepared with component ratios shown
in Table 2. Properties of cured bodies measured as described above are also shown
in Table 2.

Industrial Applicability
[0067] The curable organopolysiloxane composition of the invention can be used as a sealant
and a bonding agent for optical semiconductor elements of LEDs, semiconductor lasers,
photodiodes, photo transistors, solid-state image pickup elements, photo-coupler light
emitters and receivers, etc. The optical semiconductor devices of the invention may
be used as optical devices, optical instruments, lighting devices, illumination devices,
or similar optical semiconductor devices.